1. Field of the Invention
This invention relates to solids handling, and more particularly to methods and apparatus for introducing particulated solids into the bottom of a solids upflow vessel such as a vertical solids upflow retort vessel used for heat treating oil-producing or oil-containing solids to recover oil and/or gas therefrom.
2. Description of the Prior Art
The problem of transporting particulated solids from a solids feed supply such as a bin or reservoir of the particulated solids into the bottom of a solids upflow vessel has been encountered in diverse operations, exemplary of which are the feeding of oil-producing and/or gas-producing solids such as oil shale, tar sand, bituminous coal, oil-saturated diatomaceous earth, and the like into the bottom of a vertical solids upflow retort for treating the solids to recover oil and/or gas therefrom, and the production of synthesis gas by the reaction of gas containing steam with carbonaceous solids such as coal, coke, and the like.
In these operations, difficulties are encountered in the design and operation of mechanical feed systems because of the nature of the particulated solids being transported, typical solids being abrasive and difficult to handle on the one hand, and on the other being friable and tending to abrade, thereby forming large quantities of undesirable fine particles. Feeder devices used to introduce solids into the bottom of an upflow solids bed must move the solids against the weight of the solids bed. Also, it is often the case that the solids must be transported from a storage bin at atmospheric pressure into a solids upflow vessel which operates at a superatmospheric pressure. These factors, coupled with the often gigantic size of the equipment required to obtain the desired solids feed capacity, and the fact that in some applications the feeder device must operate at elevated temperatures and in contact with liquids and/or gases produced in the solids treating process, produce difficult design problems involving large and complex mechanical forces and complicated mechanical loadings that must be adequately provided for in the feeder design.
A number of different solids feeders for introducing solids into the bottom of a vertical solids upflow vessel have been proposed in the patent literature. Typical of these are U.S. Pat. No. 2,501,153 to Berg which discloses a solids upflow oil shale retort in which the particulated oil shale is introduced into the bottom of the vertical retort by means of a piston reciprocating in a cylinder that is oscillated between the shale feed hopper and the retort inlet. The cylinder is moved into an inclined or canted position below the shale feed hopper and the piston retracted to permit the particulated oil shale to flow by gravity into the cylinder. The cylinder is then oscillated into a vertical position below the retort and the piston moved upwardly to charge the oil shale into the bottom of the retort forcing the entire bed of solids in the retort upward, retorted oil shale being withdrawn from the top of the bed. The feed cylinder is oscillated between the shale feed hopper and the retort inlet by means of a gear and pin drive assembly. U.S. Pat. No. 2,640,014 to Berg discloses a hydraulically oscillating cylinder bottom feeder in which the feeder piston is driven by a hydraulic power cylinder. The feeder is pivotally mounted on a trunion and oscillated between the feed hopper and the bottom inlet of the retort by means of a second hydraulic power cylinder acting laterally upon the bottom of the feed cylinder. U.S. Pat. No. 2,875,137 to Lieffers et al. discloses another embodiment of such device in which the feed cylinder is pivotally mounted on a bottom trunion and oscillated between the shale feed hopper and the retort inlet by means of a second hydraulic power cylinder acting laterally on the top of the feed cylinder. This latter embodiment was successfully employed in a small 2,000 tons per day prototype oil shale retort.
While oscillating cylinder feeders of the type disclosed in the Berg and Lieffers et al. patents can be satisfactorily employed to introduce particulated solids into the bottom of a solids upflow vessel, a number of serious problems and limitations are encountered when utilizing feeders of this type in large capacity commerical units such as solids upflow oil shale retorts having capacities in the range of 10,000 tons per day, or more. Specifically, the oscillating cylinder feeders for these capacities are extremely large and require substantial clearance between the foundation and the bottom of the retort, increasing the height of the retort structure and adding substantial cost. The clearance between the arcuate shale guard and the bottom of the shale hopper and the retort must be extremely close, i.e., in the range of 0.005 inches or less. Machining of the parts to these close tolerances cannot be readily obtained, and at best is extremely costly. Also, the capacities of single cylinder feeders are limited, and high capacities require extremely large units operating at relatively high speeds. Furthermore, it is difficult to fill the feed cylinder when it is in the inclined or canted position, and the oscillating cylinder feeders have reduced volumetric efficiency. These factors all contribute to the complexity of the mechanical design, increase the cost, and reduce the operating efficiency of this type of solids feeder.
Various other solids feeder systems have been proposed, exemplary of which are those described in U.S. Pat. Nos. 300,385 to Matieu and 2,029,760 to Derby et al. German Pat. No. 144,436 discloses a manually operated device for stoking a boiler with coal which includes a piston-containing cylinder into which the coal is loaded and a lever mechanism for moving the cylinder horizontally into position below the fire box and driving the piston upwardly to force the coal into the bottom of the bed of burning coal. While such device may have application in firing small boilers, it is wholly unsuited for feeding particulated solids into the bottom of a large capacity solids upflow vessel, which may be operated at superatmosphere pressure.
Thus, need exists for a relatively inexpensive, reliable, high capacity, solids feeder for introducing particulated solids into the bottom of a solids upflow vessel, and particularly into the bottom of a vertical solids upflow retort vessel useful for heat treating oil-producing or oil-containing solids to recover oil and/or gas therefrom.
Accordingly, a principal object of this invention is to provide a solids feeder for introducing particulated solids into the bottom of a solids upflow vessel.
Another object of the invention is to provide a solids feeder for introducing particulated solids into the bottom of a solids upflow vessel at relatively high charge rates.
Still another object of the invention is to provide a solids feeder having a high volumetric efficiency.
A still further object of the invention is to provide a high capacity solids feeder for introducing particulated solids into the bottom of a solids upflow vessel in which close mechanical clearances, high bearing loadings, high mechanical stresses, and high speed movement of mechanical parts are minimized.
Yet another object of the invention is to provide a solids feeder for introducing particulated oil shale into the bottom of a solids upflow, fluid downflow retort operating at superatmospheric pressure.
Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the appended drawings.